SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3aa1f3c32cff58341679728b1a5b2b5e68c29b569e93c224f5ccfa3e9ae2727' 
  AND token = 'w35CgYSR4mo/qadRhrU40QvhzTTI2qHsodqpji/g4HQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}